Spectrum spread communication system

• US 6,195,343 B1
• Filed: 03/12/1997
• Issued: 02/27/2001
• Est. Priority Date: 03/15/1996
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Watanabe, Masatoshi
• Primary Examiner(s): Rao, Seema S.
• Application Number:
  US08/820,363
• Time in Patent Office: 1,448 Days
• Field of Search: 370/315, 370/320, 370/324, 370/328, 370/329, 370/331, 370/335, 370/342-345, 370/350, 370/503, 370/506-512, 370/514, 370/515, 370/516, 375/362-364, 375/367, 375/368, 375/208, 375/366, 375/354-357, 375/145, 455/422, 455/426, 455/450-452, 455/500, 455/501, 455/507, 455/509-514, 455/517, 455/524, 455/525, 714/707, 714/751, 714/755, 714/775-776, 714/786, 714/789, 714/790, 714/794, 714/798
• US Class Current: 370/335
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04L 7/043 Pseudo-noise [PN] codes variable during transmission synchronisation of spread spectrum receivers H04B1/69
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

In base station side equipment, a control channel for transmitting control information and a communication channel for transmitting information to each mobile station are spread with different synchronizing codes before being superposed by operating a switch to switch the output of an adder over to the output of a synchronizing code generator. Further, a synchronizing code is periodically inserted in a signal by one symbol length and the signal is transmitted over the superposed channel. In a plurality of base station side equipment, moreover, the synchronizing code and its transmission period are equal and the transmission timing is asynchronous and independent. A synchronizing correlator in mobile station side equipment obtains the correlation value of the whole chip phase in a synchronizing code transmission period using the synchronizing code and decides a base station which is transmitting the synchronizing code at the greatest correlating peak position to the closest one and further extracts symbol timing from the peak position.

Claims

1. A spectrum spread communication system comprising:

a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code;

wherein each of said plurality of base stations employs a combination of a short code, whose symbol length is equal to said synchronizing code length, and a long code, whose period is longer than that of the short code, as a spread code for use in a channel for transmitting information and as a control signal to the mobile stations, the synchronizing code transmission period being equal to the long code period, the synchronizing code conforming to the leading end of the long code;

wherein each of said plurality of mobile stations uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to acquire long code synchronization;

wherein kinds of synchronizing codes and transmission frequencies of all said plurality of base stations are equalized, different long codes are allocated to adjacent base stations; and

further wherein each of said plurality of mobile stations detects the correlation of the synchronizing code over the whole phase of the synchronizing code transmission period to determine a closest base station which transmitting the synchronizing code whose correlation value is the highest, uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to detect the correlation of the whole long code allocated to the closest base station, and acquires long code synchronization by deciding a long code with the greatest correlation value to be the long code of the closest base station.

2. A spectrum spread communication system comprising:

a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code;

wherein each of said plurality of base stations employs a combination of a short code, whose symbol length is equal to said synchronizing code length, and a long code, whose period is longer than that of the short code, as a spread code for use in a channel for transmitting information and as a control signal to the mobile stations, the synchronizing code transmission period being equal to the long code period, the synchronizing code conforming to the leading end of the long code;

wherein each of said plurality of mobile stations uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to acquire long code synchronization

wherein kinds of synchronizing codes and transmission frequencies of all of said plurality of base stations are equalized, and synchronizing code transmission sections are prevented from being overlapped at adjoining base stations; and

further wherein each of said plurality of mobile stations detects the correlation of the synchronizing code over the whole phase of the synchronizing code transmission period to determine a closest base station which transmits the synchronizing code whose correlation value is the highest, uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to detect the correlation of the whole long code allocated to the closest base station, and acquires long code synchronization by deciding a long code with the greatest correlation value to be the long code of the closest base station.

3. A spectrum spread communication system comprising:

a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code; and

wherein each of said plurality of mobile stations has means for obtaining the delay profile of a propagation path between said mobile station and said base station by detecting the correlation value of the whole chip phase in the synchronizing code.

4. A spectrum spread communication system comprising:

a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code; and

wherein said mobile stations have means for detecting the phase angle of the propagation path of the received signal by using the result of detection of the correlation of the synchronizing code.

5. A spectrum spread communication system comprising:

a plurality of base stations and a plurality of mobile stations having communication means using a direct spread CDMA (Code Division Multiple Access) method as a multi-dimensional access method, each of said plurality of base stations having synchronizing code transmission means for periodically transmitting a synchronizing code together with a specific spread code, said specific spread code having a length which is integer times as great as a transmission symbol length of the synchronizing code, each of said plurality of mobile stations having means for acquiring symbol synchronization of the base stations by detecting correlation of the synchronizing code;

wherein each of said plurality of base stations employs a combination of a short code, whose symbol length is equal to said synchronizing code length, and a long code, whose period is longer than that of the short code, as a spread code for use in a channel for transmitting information and as control signal to the mobile stations, the synchronizing code transmission period being equal to the long code period, the synchronizing code conforming to the leading end of the long code;

wherein each of said plurality of mobile stations uses the synchronizing code transmission period and timing obtained by detecting the correlation of the synchronizing code to acquire long code synchronization;

wherein said base stations have means for effecting error correcting coding with respect to the information transmitted to the plurality of base stations and means for replacing and transmitting the synchronizing code with part of data after the error correcting coding; and

further wherein said mobile stations have means for decoding the received error correcting code.

6. A spectrum spread communication system as claimed in claim 5, wherein each of said plurality of mobile stations effect punctured decoding without using the received data corresponding to the synchronizing code transmission section for decoding.